Objective To explore whether ginsenoside Rg1 can attenuate β-amyloid peptide 2535induced Tau hyperphosporylation in rat embryo cortical neurons by regulating the activity of GSK-3β and PP2A. Methods Primary cultures of cortical neurons were prepared from the embryonic day 18±2 in SpragueDawley rats. The experimental groups were designed as follows:1.Neurons culture (control group); 2. Neurons exposed to 20μmol/L Aβ25-35 for 12 hours (Aβ-model group); 3.Neurons exposed to 20μmol/L Aβ25-35 and 10 mmol/L lithium chloride (LiCl), a specific inhibitor of glycogen synthase kinase3β（GSK-3β）, for 12 hours (LiCl group); 4.Neurons exposed to 20μmol/L Aβ25-35 for 12 hours in the presence of 24hour pretreatment with ginsenoside Rg1 (Rg1 pretreatment group) . Western blotting and immunocytochemical staining were used to detect the levels of Tau phosphorylation，total Tau and GSK-3β in cortical neurons. Nonradioimmunoassay was introduced to detect the activity of protein phosphatase 2A (PP2A). Results In Aβ-model group, the levels of Tau protein phosphorylation in the sites of Ser396，Ser199/202，Thr231 and total Ta